Multi-speed transmission having three planetary gear sets

ABSTRACT

A transmission is provided having an input member, an output member, three planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices include clutches and brakes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/030,259, filed on Feb. 21, 2008. The disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The invention relates generally to a multiple speed transmission havinga plurality of planetary gear sets and a plurality of torquetransmitting devices and more particularly to a transmission having nineor more speeds, three planetary gear sets and a plurality of torquetransmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of frictionclutches, planetary gear arrangements and fixed interconnections toachieve a plurality of gear ratios. The number and physical arrangementof the planetary gear sets, generally, are dictated by packaging, costand desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

A transmission is provided having an input member, an output member,three planetary gear sets, a plurality of coupling members and aplurality of torque transmitting devices. Each of the planetary gearsets includes first, second and third members. The torque transmittingdevices are for example clutches and brakes.

In another embodiment of the transmission, the transmission has an inputmember, an output member, first, second, and third planetary gear sets.Each of the planetary gear sets has a sun gear, carrier and ring gearmembers. The input member is continuously interconnected to the sun gearmember of the first planetary gear set and the output member iscontinuously interconnected to the ring gear member of the thirdplanetary gear set.

Moreover, a first interconnecting member continuously interconnects thering gear member of the first planetary gear set with the carrier memberof the second planetary gear set. A second interconnecting membercontinuously interconnects the ring gear member of the second planetarygear set with the sun gear member of the third planetary gear set.

Additionally, a first torque transmitting mechanism is selectivelyengageable to interconnect the sun gear member of the first planetarygear set with the carrier member of the third planetary gear set. Asecond torque transmitting mechanism is selectively engageable tointerconnect the carrier member of the first planetary gear set with thecarrier member of the third planetary gear set. A third torquetransmitting mechanism is selectively engageable to interconnect thering gear member of the first planetary gear set with the ring gearmember of the third planetary gear set. A fourth torque transmittingmechanism is selectively engageable to interconnect the ring gear memberof the first planetary gear set with the sun gear member of the secondplanetary gear set. A fifth torque transmitting mechanism is selectivelyengageable to interconnect the carrier member of the first planetarygear set with the stationary element. A sixth torque transmittingmechanism is selectively engageable to interconnect the sun gear memberof the second planetary gear set with the stationary element. The torquetransmitting mechanisms are selectively engageable in combinations of atleast three to establish at least nine forward speed ratios and at leastone reverse speed ratio between the input member and the output member.

Thus, it is an object of the present invention to provide a transmissionhaving at least nine forward speeds and at least one reverse.

It is further an object of the present invention to provide atransmission having three planetary gear sets, a plurality of couplingmembers and a plurality of torque transmitting devices.

Further objects, aspects and advantages of the present invention willbecome apparent by reference to the following description and appendeddrawings wherein like reference numbers refer to the same component,element or feature.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a lever diagram of an embodiment of a nine speed transmissionaccording to the present invention;

FIG. 2 is a diagrammatic illustration of an embodiment of a nine speedtransmission according to the present invention; and

FIG. 3 is a truth table presenting the state of engagement of thevarious torque transmitting elements in each of the available forwardand reverse speeds or gear ratios of the transmission illustrated inFIGS. 1 and 2.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

At the outset, it should be appreciated that the embodiments of the ninespeed automatic transmission of the present invention have anarrangement of permanent mechanical connections between the elements ofthe three planetary gear sets. A first component or element of a firstplanetary gear set is permanently coupled to a second component orelement of the second planetary gear set. A first component or elementof a second planetary gear set is permanently coupled to a firstcomponent or element of the third planetary gear set.

Referring now to FIG. 1, an embodiment of a nine speed transmission 10is illustrated in a lever diagram format. A lever diagram is a schematicrepresentation of the components of a mechanical device such as anautomatic transmission. Each individual lever represents a planetarygear set wherein the three basic mechanical components of the planetarygear are each represented by a node. Therefore, a single lever containsthree nodes: one for the sun gear, one for the planet gear carrier, andone for the ring gear. The relative length between the nodes of eachlever can be used to represent the ring-to-sun ratio of each respectivegear set. These lever ratios, in turn, are used to vary the gear ratiosof the transmission in order to achieve an appropriate ratios and ratioprogression. Mechanical couplings or interconnections between the nodesof the various planetary gear sets are illustrated by thin, horizontallines and torque transmitting devices such as clutches and brakes arepresented as interleaved fingers. Further explanation of the format,purpose and use of lever diagrams can be found in SAE Paper 810102, “TheLever Analogy: A New Tool in Transmission Analysis” by Benford andLeising which is hereby fully incorporated by reference.

The transmission 10 includes an input shaft or member 12, a firstplanetary gear set 14 having three nodes: a first node 14A, a secondnode 14B and a third node 14C, a second planetary gear set 16 havingthree nodes: a first node 16A, a second node 16B and a third node 16Cand a third planetary gear set 18 having three nodes: a first node 18A,a second node 18B and an output shaft or member 22.

The input member 12 is coupled to the third node 14C of the firstplanetary gear set 14. The output member 22 is coupled to the third node18C of the third planetary gear set 18. The first node 14A of the firstplanetary gear set 14 is coupled to the second node 16B of the secondplanetary gear set 16. The first node 16A of the second planetary gearset 16 is coupled to the first node 18A of the third planetary gear set18.

A first clutch 26 selectively connects the third node 14C of the firstplanetary gear set 14 with the second node 18B of the third planetarygear set 18. A second clutch 28 selectively connects the second node 14Bof the first planetary gear set 14 with the second node 18B of the thirdplanetary gear set 18. A third clutch 30 selectively connects the firstnode 14A of the first planetary gear set 14 and the second node 16B ofthe second planetary gear set 16 with the output member 22. A fourthclutch 32 selectively connects the first node 14A of the first planetarygear set 14 and the second node 16B of the second planetary gear set 16with the third node 16C of the second planetary gear set 16. A firstbrake 34 selectively connects the second node 14B of the first planetarygear set 14 to a stationary member or transmission housing 50. A secondbrake 36 selectively connects the third node 16C of the second planetarygear set 16 to a stationary member or transmission housing 50.

Referring now to FIG. 2, a stick diagram presents a schematic layout ofthe embodiment of the nine speed transmission 10 according to thepresent invention. In FIG. 2, the numbering from the lever diagram ofFIG. 1 is carried over. The clutches and couplings are correspondinglypresented whereas the nodes of the planetary gear sets now appear ascomponents of planetary gear sets such as sun gears, ring gears, planetgears and planet gear carriers.

For example, the planetary gear set 14 includes a sun gear member 14C, aring gear member 14A and a planet gear carrier member 14B that rotatablysupports a set of planet gears 14D (only one of which is shown). The sungear member 14C is connected for common rotation with a first shaft orintermediate member 42 and with input shaft or member 12. The ring gearmember 14A is connected for common rotation with a second shaft orintermediate member 44. The planet carrier member 14B is connected forcommon rotation with a third shaft or intermediate member 46 and afourth shaft or intermediate member 48. The set of planet gears 14D areconfigured to intermesh with both the sun gear member 14C and the ringgear member 14A.

The planetary gear set 16 includes a sun gear member 16C, a ring gearmember 16A and a planet gear carrier member 16B that rotatably supportsa set of planet gears 16D (only one of which is shown). The sun gearmember 16C is connected for common rotation with a fifth shaft orintermediate member 52. The ring gear member 16A is connected for commonrotation with a sixth shaft or intermediate member 54. The planetcarrier member 16B is connected for common rotation with the secondshaft or intermediate member 44 and a seventh shaft or intermediatemember 56. The planet gears 16D are configured to intermesh with boththe sun gear member 16A and the ring gear member 16C.

The planetary gear set 18 includes a sun gear member 18A, a ring gearmember 18C and a planet gear carrier member 18B that rotatably supportsa set of planet gears 18D (only one of which is shown). The sun gearmember 18A is connected for common rotation with sixth shaft orintermediate member 54. The ring gear member 18C is connected for commonrotation with output shaft or member 22 and a ninth shaft orintermediate member 59. The planet carrier member 18B is connected forcommon rotation with an eighth shaft or intermediate member 58. Theplanet gears 18D are configured to intermesh with both the sun gearmember 18A and the ring gear member 18C.

The input shaft or member 12 is continuously connected to an engine (notshown) or to a turbine of a torque converter (not shown). The outputshaft or member 22 is continuously connected with the final drive unitor transfer case (not shown).

The torque-transmitting mechanisms or clutches 26, 28, 30, 32 and brakes34 and 36 allow for selective interconnection of the shafts orinterconnecting members, members of the planetary gear sets and thehousing. For example, the first clutch 26 is selectively engageable toconnect the first shaft or intermediate member 42 with the eighth shaftor intermediate member 58. The second clutch 28 is selectivelyengageable to connect the fourth shaft or intermediate member 48 withthe eighth shaft or intermediate member 58. The third clutch 30 isselectively engageable to connect the seventh shaft or intermediatemember 56 with the ninth shaft or intermediate member 59. The fourthclutch 32 is selectively engageable to connect the second shaft orintermediate member 44 with the fifth shaft or intermediate member 52.The first brake 34 is selectively engageable to connect the third shaftor intermediate member 46 with the stationary element or thetransmission housing 50 in order to restrict the member 46 from rotatingrelative to the transmission housing 50. The second brake 36 isselectively engageable to connect the fifth shaft or intermediate member52 with the stationary element or the transmission housing 50 in orderto restrict the member 52 from rotating relative to the transmissionhousing 50.

Referring now to FIG. 2 and FIG. 3, the operation of the embodiment ofthe nine speed transmission 10 will be described. It will be appreciatedthat transmission 10 is capable of transmitting torque from the inputshaft or member 12 to the output shaft or member 22 in at least nineforward speed or torque ratios and at least one reverse speed or torqueratio with triple overdrive. Each forward and reverse speed or torqueratio is attained by engagement of one or more of thetorque-transmitting mechanisms (i.e. first clutch 26, second clutch 28,third clutch 30, fourth clutch 32, first brake 34 and second brake 36),as will be explained below. FIG. 3 is a truth table presenting thevarious combinations of torque-transmitting mechanisms that areactivated or engaged to achieve the various gear states. An “X” in thebox means that the particular clutch or brake is engaged to achieve thedesired gear state. An “O” represents that the particular torquetransmitting device (i.e. a brake or clutch) is on or active, but notcarrying torque. Actual numerical gear ratios of the various gear statesare also presented although it should be appreciated that thesenumerical values are exemplary only and that they may be adjusted oversignificant ranges to accommodate various applications and operationalcriteria of the transmission 10. An example of the gear ratios that maybe obtained using the embodiments of the present invention are alsoshown in FIG. 3. Of course, other gear ratios are achievable dependingon the gear diameter, gear teeth count and gear configuration selected.

To establish a reverse gear, the third clutch 30, first brake 34 andsecond brake 36 are engaged or activated. The third clutch 30 connectsthe seventh shaft or intermediate member 56 with the seventh shaft orintermediate member 56. The first brake 34 connects the third shaft orintermediate member 46 with the stationary element or the transmissionhousing 50 in order to restrict the member 46 from rotating relative tothe transmission housing 50. The second brake 36 connects the fifthshaft or intermediate member 52 with the stationary element or thetransmission housing 50 in order to restrict the member 52 from rotatingrelative to the transmission housing 50. Likewise, the nine forwardratios are achieved through different combinations of clutch and brakeengagement, as shown in FIG. 3.

It will be appreciated that the foregoing explanation of operation andgear states of the nine speed transmission 10 assumes, first of all,that all the clutches not specifically referenced in a given gear stateare inactive or disengaged and, second of all, that during gear shifts,i.e., changes of gear state, between at least adjacent gear states, aclutch engaged or activated in both gear states will remain engaged oractivated.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; first,second, and third planetary gear sets each having first, second andthird members, wherein the input member is continuously interconnectedto the third member of the first planetary gear set and the outputmember is continuously interconnected to the third member of the thirdplanetary gear set; a first interconnecting member continuouslyinterconnecting the first member of the first planetary gear set withthe second member of the second planetary gear set; a secondinterconnecting member continuously interconnecting the first member ofthe second planetary gear set with the first member of the thirdplanetary gear set; and six torque transmitting mechanisms selectivelyengageable to interconnect one of the first, second, and third memberswith another of the first, second, third members and a stationaryelement, and wherein the torque transmitting mechanisms are selectivelyengageable in combinations of at least three to establish at least nineforward speed ratios and at least one reverse speed ratio between theinput member and the output member.
 2. The transmission of claim 1wherein a first of the six torque transmitting mechanisms is selectivelyengageable to interconnect the third member of the first planetary gearset with the second member of the third planetary gear set.
 3. Thetransmission of claim 2 wherein a second of the six torque transmittingmechanisms is selectively engageable to interconnect the second memberof the first planetary gear set with the second member of the thirdplanetary gear set.
 4. The transmission of claim 3 wherein a third ofthe six torque transmitting mechanisms is selectively engageable tointerconnect the third member of the third planetary gear set and theoutput member with at least one of the second member of the secondplanetary gear set and the first member of the first planetary gear set.5. The transmission of claim 4 wherein a fourth of the six torquetransmitting mechanisms is selectively engageable to interconnect atleast one of the first member of the first planetary gear set and thesecond member of the second planetary gear set with the third member ofthe second planetary gear set.
 6. The transmission of claim 5 wherein afifth of the six torque transmitting mechanisms is selectivelyengageable to interconnect the second member of the first planetary gearset with the stationary element.
 7. The transmission of claim 6 whereina sixth of the six torque transmitting mechanisms is selectivelyengageable to interconnect the third member of the second planetary gearset with the stationary element.
 8. The transmission of claim 1 whereinthe third member of the first and second planetary gear sets and thefirst member of the third planetary gear set are sun gears, the secondmembers of the first, second and third planetary gear sets are carriermembers, and the first members of the first and second planetary gearsets and the third member of the third planetary gear set are ringgears.
 9. The transmission of claim 1 wherein two of the torquetransmitting mechanisms are brakes for connecting a plurality of thefirst, second, and third members to the stationary element and four ofthe torque transmitting mechanisms are clutches for connecting a set ofthe first, second, and third members to another set of the first,second, and third members.
 10. A transmission comprising: an inputmember; an output member; first, second, and third planetary gear setseach having first, second and third members, wherein the input member iscontinuously interconnected to the third member of the first planetarygear set and the output member is continuously interconnected to thethird member of the third planetary gear set; a first interconnectingmember continuously interconnecting the first member of the firstplanetary gear set with the second member of the second planetary gearset; a second interconnecting member continuously interconnecting thefirst member of the second planetary gear set with the first member ofthe third planetary gear set; a first torque transmitting mechanismselectively engageable to interconnect the third member of the firstplanetary gear set with the second member of the third planetary gearset; a second torque transmitting mechanism selectively engageable tointerconnect the second member of the first planetary gear set with thesecond member of the third planetary gear set; a third torquetransmitting mechanism selectively engageable to interconnect the thirdmember of the third planetary gear set and the output member with atleast one of the second member of the second planetary gear set and thefirst member of the first planetary gear set; a fourth torquetransmitting mechanism selectively engageable to interconnect at leastone of the first member of the first planetary gear set and the secondmember of the second planetary gear set with the third member of thesecond planetary gear set; a fifth torque transmitting mechanismselectively engageable to interconnect the second member of the firstplanetary gear set with the stationary element; and a sixth torquetransmitting mechanism selectively engageable to interconnect the thirdmember of the second planetary gear set with the stationary element,wherein the torque transmitting mechanisms are selectively engageable incombinations of at least three to establish at least nine forward speedratios and at least one reverse speed ratio between the input member andthe output member.
 11. The transmission of claim 10 wherein the thirdmember of the first and second planetary gear sets and the first memberof the third planetary gear set are sun gears, the second members of thefirst, second and third planetary gear sets are carrier members, and thefirst members of the first and second planetary gear sets and the thirdmember of the third planetary gear set are ring gears.
 12. Atransmission comprising: an input member; an output member; first,second, and third planetary gear sets each having sun gear, carrier andring gear members, wherein the input member is continuouslyinterconnected to the sun gear member of the first planetary gear setand the output member is continuously interconnected to the ring gearmember of the third planetary gear set; a first interconnecting membercontinuously interconnecting the ring gear member of the first planetarygear set with the carrier member of the second planetary gear set; asecond interconnecting member continuously interconnecting the ring gearmember of the second planetary gear set with the sun gear member of thethird planetary gear set; a first torque transmitting mechanismselectively engageable to interconnect the sun gear member of the firstplanetary gear set with the carrier member of the third planetary gearset; a second torque transmitting mechanism selectively engageable tointerconnect the carrier member of the first planetary gear set with thecarrier member of the third planetary gear set; a third torquetransmitting mechanism selectively engageable to interconnect the ringgear member of the third planetary gear set and the output member withat least one of the carrier member of the second planetary gear set andthe ring gear member of the first planetary gear set; a fourth torquetransmitting mechanism selectively engageable to interconnect at leastone of the ring gear member of the first planetary gear set and thecarrier member of the second planetary gear set with the sun gear memberof the second planetary gear set; a fifth torque transmitting mechanismselectively engageable to interconnect the carrier member of the firstplanetary gear set with the stationary element; and a sixth torquetransmitting mechanism selectively engageable to interconnect the sungear member of the second planetary gear set with the stationaryelement, wherein the torque transmitting mechanisms are selectivelyengageable in combinations of at least three to establish at least nineforward speed ratios and at least one reverse speed ratio between theinput member and the output member.